1. Field of the Invention
This invention relates to a semiconductor device and its manufacturing method, specifically to a chip size package and its manufacturing method.
2. Description of the Related Art
A CSP (Chip Size Package) has received attention in recent years as a new packaging technology. The CSP means a small package having about the same outside dimensions as those of a semiconductor die packaged in it.
A BGA (Ball Grid Array) type semiconductor device is known as a kind of chip size package device. An example structure of the BGA type semiconductor device is described hereafter.
A pad electrode 112 is disposed on an insulation film 111 disposed on a top surface of a semiconductor substrate 110 that constitutes the semiconductor device, as shown in a cross-sectional view of FIG. 14. The pad electrode 112 is connected with an electronic device (not shown) formed in the semiconductor substrate 110. The pad electrode 112 is covered with an insulation film 113 that makes a passivation film. A supporter 115 is bonded to the top surface of the semiconductor substrate 110 through an adhesive layer 114.
On the other hand, an opening 110A is formed from a back surface of the semiconductor substrate 110 in a region overlapping the pad electrode 112 and a dicing line DL. An insulation film 116 is formed in an inside of the opening 110A and over the back surface of the semiconductor substrate 110. An opening 117 that exposes a portion of the pad electrode 112 is formed in the insulation films 111 and 116 that overlap the pad electrode 112. On the insulation film 116, there is disposed a wiring layer 118 that is connected with the pad electrode 112 through the opening 117. The wiring layer 118 is covered with an insulation film 119 and a protection film 120. An opening that exposes a portion of the wiring layer 118 is provided in the insulation film 119 and the protection film 120 that overlap the wiring layer 118. A plating layer 121 made of gold plating, for example, is disposed on the wiring layer 118 in the opening. A bump electrode 122 is disposed on the plating layer 121.
A groove 123 extending partway through a thickness of the supporter 115 is formed along the dicing line DL in the opening 110A in the semiconductor substrate. The protection film 120 covers the groove 123. The structure as described above eliminates a possibility that a damaged layer which allows invasion of water or the like to corrode the pad electrode 112 in the semiconductor device after dicing is caused on a side surface of the semiconductor substrate 110. Also, there can be prevented a connection failure between the pad electrode 112 and the wiring layer 118 due to an impact caused when a dicing blade touches the semiconductor substrate 110.
The structure described above looks as shown in FIG. 15 when looked from a back surface-side of the semiconductor substrate 110. A cross-sectional view of a section Y-Y in FIG. 15 corresponds to FIG. 14. FIG. 15 shows only the semiconductor substrate 110, the openings 110A, the openings 117, the bump electrodes 122 and the dicing lines DL out of the components shown in FIG. 14, and the rest of the components are omitted for the sake of convenience of the explanation.
The BGA type semiconductor device is described in Japanese Patent Application Publication No. 2005-72554, for example.
As described above, there is a need to secure a region corresponding to a width of the groove 123 between a pair of the pad electrodes 112 astride the dicing line DL in order to prevent the corrosion of the pad electrode 112 and the connection failure between the pad electrode 112 and the wiring layer 118, when the groove 123 is formed along the dicing line DL and covered with the protection film 120. That is, the conventional semiconductor device requires an additional area of the semiconductor substrate 110 to form each of the semiconductor devices. As a result, the number of the semiconductor devices obtained from a wafer form of the semiconductor substrate 110 has been reduced. In addition, the forming of the groove 123 has made the manufacturing process of the semiconductor device more complicated to increase the manufacturing cost. Furthermore, the reliability of the semiconductor device has been reduced because the pad electrodes 112 are disposed outside a guard ring GR that protects internal components by surrounding them.